This blog is a little effort to make biotechnology concepts simplified to all the students in the degree classes from all the universities.I took the initiative to make concise and well formulated notes supported with the diagrams.I have struggled a lot in making notes and searching for the concepts by digging library books and surfing various sites. All i want is to create one place where you can look up to biotechnology notes and rely upon them as i have put up a lot of effort on them.

Tuesday, 6 December 2011

PENICILLIN PRODUCTION

PENICILLIN PRODUCTION:

Penicillin was
the first naturally occurring antibiotic discovered. It is obtained in a number
of forms from Penicillium moulds. Penicillin is not a single compound but a
group of closely related compounds, all with the same basic ring-like structure
(a β-lactam) derived from two amino acids (valine and cysteine) via a
tripeptide intermediate. The third amino acid of this tripeptide is replaced by
an acyl group (R) and the nature of this acyl group produces specific
properties on different types of penicillin.

There are two
different types of penicillin.

Biosynthetic
penicillin is natural penicillin that is harvested from the mould
itself through fermentation.

Semi-synthetic penicillin includes semi
synthetic derivatives of penicillin - like Ampicillin, Penicillin V,
Carbenicillin, Oxacillin, Methicillin, etc. These compounds consist of the
basic Penicillin structure, but have been purposefully modified chemically by
removing the acyl group to leave 6-aminopenicillanic acid and then adding acyl
groups that produce new properties.

These modern
semi-synthetic penicillins have various specific properties such as resistance
to stomach acids so that they can be taken orally, a degree of resistance to penicillinase
(or β-lactamase) (a penicillin-destroying enzyme produced by some bacteria) and
an extended range of activity against some Gram-negative bacteria. Penicillin G
is the most widely used form and the same one we get in a hypodermic form.

PENICILLIN G

Penicillin G is
not stable in the presence of acid (acid-labile). Since our stomach has a lot
of hydrochloric acid in it (pH2.0), if we were to ingest penicillin G, the
compound would be destroyed in our stomach before it could be absorbed into the
bloodstream, and would therefore not be any good to us as a treatment for
infection somewhere in our body. It is for this reason that penicillin G must
be taken by intramuscular injection - to get the compound in our bloodstream,
which is not acidic at all. Many of the semi-synthetic penicillins can be taken
orally.

Penicillium
chrysogenum that
produce antibiotics, enzymes or other secondary metabolites frequently
require precursors like purine/pyrimidine bases or organic acids to produce
said metabolites. Primary metabolism is the metabolism of energy production for
the cell and for its own biosynthesis. Typically, in aerobic organisms (Penicillium
chrysogenum) it involves the conversion of sugars such as glucose to
pyruvic acid2 and the production of energy via the TCA cycle. Secondary
metabolism regards the production of metabolites that are not used in energy
production for example penicillin from Penicillium chrysogenum. In this
case the metabolite is being utilized as a defence mechanism against other
microorganisms in the environment. In essence Penicillium chrysogenum can
kill off the competition to allow itself to propagate efficiently. It should be
noted that these secondary metabolites are only produced in times of stress
when resources are low and the organism must produce these compounds to kill
off its competitors to allow it to survive.

MEDIA
FORMULATION:

Lactose: 1%

Calcium
Carbonate: 1%

Cornsteep Liquor:
8.5%

Glucose: 1%

Phenyl acetic
acid: 0.5g

Sodium hydrogen
phosphate: 0.4%

Antifoaming
Agent: Vegetable oil

FERMENTATION

To begin the
fermentation process, a number of these spores will be introduced into a small
(normally 250-500ml) conical flask where it will be incubated for several days.
At this stage, explosive growth is the most desired parameter and as such the
medium in the flask will contain high amounts of easily utilisable carbon and
nitrogen sources, such as starch and corn-steep liquor. At this stage, the
spores will begin to revive and form vegetative cells. Temperature is normally
maintained at 23-280C and pH at ~6.5, although there may be some changes made
to facilitate optimum growth. The flask will often have baffles in it and be on
a shaking apparatus to improve oxygen diffusion in the flask.

Once the overall
conditions for growth have been established and there is a viable vegetative
culture active inside the flask, it will be transferred to a 1 or 2 litre bench-top
reactor. This reactor will be fitted with a number of instruments to allow
the culture to be better observed than it was in the shake flask. Typical
parameters observed include pH, temperature, and stirrer speed and dissolved
oxygen concentration. This allows tweaking of the process to occur and
difficulties to be examined. For example, there may not be enough oxygen
getting to the culture and hence it will be oxygen starved. At this point, the cells should be showing
filamentous morphology, as this is preferred for penicillin production. As
before, cell growth is priority at this stage. At this stage, growth will
continue as before, however, there are often sudden changes or loss in
performance. This can be due to changes in the morphology of the culture (Penicillium
chrysogenum is a filamentous fungi and hence pseudoplastic) that may or may
not be correctable.

At this stage
the medium being added to the reactor will change. Carbon and nitrogen will be
added sparingly alongside precursor molecules for penicillin fed-batch style.
Another note is that the presence of penicillin in the reactor is itself
inhibitory to the production of penicillin. Therefore, we must have an efficient
method for the removal of this product and to maintain constant volume in the
reactor. Other systems, such as cooling water supply, must also be considered.
If all goes well we should have penicillin ready for downstream processing. From
here it can be refined and packaged for marketing and distribution to a global
market.

About Me

Myself a researcher interested in the field of genomics and biotechnology. Apart from following my dreams i also like to engage myself in helping other newbies in the field of life sciences. This blog is just a beginning to help budding scientists; who can get full fledged notes on biotech concepts. i have tried to make concise, thoroughly explained and supported with diagrams wherever necessary.This blog helps you avoid surfing websites for the conceptual notes. I am open to the suggestions and improvements!!! Good luck and Happy learning!!!